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arXiv 2602.03702cs.LGcs.AImath.OCstat.ML
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任意时间预训练:无时间范围的学习率调度与权重平均

Anytime Pretraining: Horizon-Free Learning-Rate Schedules with Weight Averaging

Harvard University(哈佛大学);Kempner Institute at Harvard University(哈佛大学凯默纳研究所)

Alexandru Meterez, Pranav Ajit Nair, Depen Morwani, Cengiz Pehlevan, Sham Kakade

AI总结:

本研究提出了一种无需时间范围的学习率调度方法,通过权重平均实现与余弦调度相当的预训练效果。

摘要:

大型语言模型日益在连续或开放式设置中进行训练,其中总训练时间范围在事先并不已知。尽管如此,现有的大多数预训练配方并不是任意时间的:它们依赖于依赖时间范围的学习率调度和在固定计算预算下进行的大量调整。在本工作中,我们提供了一种理论分析,证明了在过参数化的线性回归中存在任意时间的学习率调度,并突出了权重平均——也称为模型合并——在实现随机梯度下降的最小最大收敛率中的核心作用。我们显示这些任意时间调度以多项式方式随时间衰减,衰减率由问题的源条件和容量条件决定。从经验上,我们评估了1.5亿和3亿参数的语言模型,在1-32倍Chinchilla规模下进行训练,将恒定学习率与权重平均和1/√t调度与权重平均与经过良好调整的余弦调度进行比较。在整个训练范围内,任意时间调度的最终损失与余弦衰减相当。综合来看,我们的结果表明,结合简单的无时间范围步长,权重平均提供了一种实用且有效的任意时间替代方案,用于大型语言模型的预训练。

英文摘要:

Large language models are increasingly trained in continual or open-ended settings, where the total training horizon is not known in advance. Despite this, most existing pretraining recipes are not anytime: they rely on horizon-dependent learning rate schedules and extensive tuning under a fixed compute budget. In this work, we provide a theoretical analysis demonstrating the existence of anytime learning schedules for overparameterized linear regression, and we highlight the central role of weight averaging - also known as model merging - in achieving the minimax convergence rates of stochastic gradient descent. We show that these anytime schedules polynomially decay with time, with the decay rate determined by the source and capacity conditions of the problem. Empirically, we evaluate 150M and 300M parameter language models trained for up to 32x Chinchilla scale, comparing constant and $1/\sqrt{t}$ schedules with weight averaging against a well-tuned cosine schedule. Across the full training range, the anytime schedules achieve comparable final loss to cosine decay. Taken together, our results suggest that weight averaging combined with simple, horizon-free step sizes offers a practical and effective anytime alternative to cosine learning rate schedules for large language model pretraining.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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